What exactly is cloud lookup

Well ofcourse the name is suggesting something and i have an idea what it might be but still i would like to have some more details

The help entry is a bit thin:

Enable Cloud Lookup - Allows you to enable or disable File Rating. (Default and recommended =Enabled)

cloud lookup checks unknown files in the cloud. A file can have 3 different ratings safe, malicious, or unknown. When an uknown file is run CIS will check the status of the file in the cloud. The cloud will return one of the 3 ratings. If the file is safe it will automatically be added to the trusted files list and be allowed to run without restriction. If the file is malicious, CIS will alert you and give you the option to clean the file or add it to the exclusions. If the file is unknown the file will be sandboxed or a HIPS alert will be given (depending on your settings)